diff --git a/js/src/jsdtracef.c b/js/src/jsdtracef.c
index b1052867f790..6f932e3c7cdf 100644
--- a/js/src/jsdtracef.c
+++ b/js/src/jsdtracef.c
@@ -54,13 +54,13 @@ static char dempty[] = "<null>";
 char *
 jsdtrace_funcclass_name(JSFunction *fun)
 {
-    JSNativeFunction *nfun;
+    JSClass *clasp;
 
     if (FUN_IS_SCRIPTED(fun))
         return dempty;
 
-    nfun = FUN_TO_NATIVE(fun);
-    return nfun->clasp ? (char *) nfun->clasp->name : dempty;
+    clasp = NATIVE_FUN_GET_CLASS(FUN_TO_NATIVE(fun));
+    return clasp ? (char *) clasp->name : dempty;
 }
 
 char *